Understanding GPS navigation traffic services

Finding the right route to your destination is only part of the challenge with a road trip, be it daily commuting or a long-distance vacation. All the planning in the world can't account for sporadic traffic congestion. As any portable navigation device (PND) shopper soon discovers, there are traffic services available for GPS units to warn of imminent slow downs and even route around a problem area.

Adding true value to the basic mapping functions, traffic services can make a GPS unit a helpful travel companion on even familiar roads. However, not all traffic services work in the same manner. Before committing to a purchase, it is important to understand the differences.

There are three basic ways to receive traffic information:

Bluetooth—The navigation device uses your cell phone to receive the traffic information, which is beamed to the unit via Bluetooth technology. This method effectively requires your cell phone to have a data package, as a constant connection is needed to ensure continuous updates along your route. There are a limited amount of compatible phones, almost exclusive to T-Mobile and Cingular. TomTom units use this approach for the TomTom PLUS services.

FM—Using the same FM Radio Data System (RDS) that delivers station IDs and song information to modern stereos, sources like Navteq and Clear Channel Radio deliver traffic updates over the airwaves. This is often referred to as RDS-TMC, for Traffic Message Channel. An external antenna may be optional to assist with reception. FM traffic is most often a premium service, although some devices, like the recently evaluated Navigon 5100, include it for free.

A new twist on the traffic sources is MSN Direct from Microsoft. An FM-based service, MSN Direct is available on just a handful of models out of the box and several more are compatible with the purchase of an additional FM receiver. This service combines traffic information with weather, movie times, and gas prices. It costs $49.95 a year, or $129.95 for the lifetime of the device. It is non-transferable.

XM—XM NavTraffic is a premium service powered by Navteq. Plans allow for a$9.95/month stand-alone fee or $3.99/month when combined with XM Radio service. Some portable devices can be used to bring XM Radio service to the car, played through an FM transmitter. While convenient, this may not be the ideal solution for audio fidelity. FM transmitters run the risk of station overlap in major metropolitan areas where the services are most likely to be available. XM requires an antenna.

Living with traffic
With a traffic service, the navigation device will receive periodic updates based on your driving path or (if entered) programmed destination. It can provide on-screen alerts and even indicate the traffic flow rate. Usually the driver can tap a traffic icon to receive info on how long the delay is, what type of obstruction (accident, construction, lane closing), and then decide whether or not to detour around a trouble-spot.  Also, general traffic in the area can often be displayed by going into the menu of the unit and just browsing the traffic incidents.

While we do not specifically test traffic performance for our ratings (available to online subscribers), we certainly have used the functions as we drive around the New York City region. The major providers have coverage in about 80 major metro areas, covering the bulk of the nation's congested areas.

Drivers benefit from these services by receiving only the information appropriate to their route, rather than having to filter through periodic, on-air traffic reports. Such radio updates tend to focus on major trouble spots and may not address the road you're on. In New York, for example, it is not uncommon for reports to be focused on the city bridges and New Jersey, areas far from where we may be driving.

Like traditional radio reports, the traffic services can be spotty and experience time delays before some information enters the corporate system and is fed to your device. A week ago, I was in bumper-to-bumper, walking-pace traffic on an Interstate for an hour before the nav system indicated a traffic slow down. ("Gee, you finally noticed," I thought.) On the other hand, driving on a smaller parkway recently, I was impressed when the same device warned there was a disabled truck just moments before I saw an 18-wheeler at the side of the road with flares around it.

Traffic services can be a real convenience, and even a time saver, but they aren't  perfect. They can, however, add value to your GPS purchase by making it more useful on a daily basis. If you are drawn to a traffic service, look at all the costs associated before choosing a device. Many systems are "traffic compatible" but require a $125 receiver. That may be money better spent on a more feature-rich unit or even one with a wide screen.

Just as with the device itself, consider how many features you will truly need from a traffic service. If you buy gas at the same local station and look online for movie times, for example, you may be able to forgo MSN Direct. Likewise, if you don't think a traffic service is truly worth paying for, put the money toward a better, non-traffic unit, or just keep it in your pocket.

—Jeff Bartlett and Frank Spinelli


For more information on portable GPS navigation systems, see our Ratings and buying advice and watch our video guide. Discuss GPS devices in the forums.

Comments

[Edward Lehman]

I recently purchased the Garmin Nuvi 660 for a trip to New York and then traveling by car from Newark New Jersey to Niagara Falls and back to Newark. The Garmin was remarkable in directing us accurately along the highways. The Garmin was easy to use and I would recommend it to all interested in purchasing a mobil GPS unit.

[john]

Is there any gps system that can plot routes for commercial vehicles??

[steve simmons]

The only gps mapping for commercial trucks I know is ProMiles software, which you would use on your laptop. It's pricy, over $250 but gives dock to dock routing. Link: http://www.promiles.com/TruckmilesCD.asp

[Mark]

I have a Nuvi 680 with the MSN service (it came with a one year free subscription). I live in the western Chicago suburbs and although the MSN coverage map indicates adequate coverage, I have found it to be spotty at best as I travel around the Chicago area. Recently I traveled to downtown Chicago and I did not get a signal until I was almost downtown. At that point it was too late as far as using the traffic info. I have found that there are certain areas where the signal is adequate but these are few and far between. In the weaker coverage areas you will get data loaded eventually but not fast enough to help you make driving decisions based on traffic and not even good enough for a display of the current temperature. The only thing I have found it good for is the 3 day weather forecast and gas prices (although these were off a few days the relative differences helped me find the cheapest gas at any given location). And one glaring omission is any indication by the device of when the last update was received; you have no idea of how fresh (or stale) the information is. This service is certainly not ready for prime time yet as I would consider Chicago a market that would be on the first to cover list. Indeed, I think the whole FM approach is the wrong direction as it is a slow, one way communication media designed for voice and music and not on demand data. In fact this is a move backwards. The medium of choice is the Internet (see Google Maps and Microsoft Live for good examples of traffic, weather, movie times, etc.). And we have a growing number of technologies that let us access it from a vehicle. GPS manufacturers should be focusing on them instead of this FM nonsense.

[mike]

In Los Angeles, ClearChannel Traffic is trying to "ground" their aircraft - and airborne reporters - that are typically used to 'verify' traffic incidents that are being reported by the Highway Patrol, users/listeners/callers, and embedded and/or overhead traffic sensors.

The "suits" in Burbank (the local main office), view the cost of having an airborne resource (including aircraft, pilots, maintenance issues, having to comply with FAA regulations [known as FARs], bad weather - and the airborne reporters), as one big fat pain and expense.

ClearChannels' local traffic service - Airwatch America (based in Santa Ana) - laid-off several reporters at the end of November 2007, claiming the aforementioned 'suits' had cut the airborne division out of the operational budget.
Later, it was discovered that one of the radio stations Airwatch America serviced had a clause in their contract that REQUIRED the traffic-reports for that station be performed from the aircraft - which forced ClearChannel to hire an airborne reporter (they did not rehire the same reporter that had been servicing that particular station - they hired a younger person that worked the same shifts for less money and on a part-time basis with no benefits).

ClearChannel has stated publicly that they would rather go with the sensors alone and forego the human element (aka: airborne reporters), that makes traffic-reporting more accurate.

That being said, most of the traffic sensors are at least 5 to 10 minutes old (after being processed).
AFter an in-house producer receives that processed information, s/he culls that information and enters it into the traffic reporting system.
By then, ANOTHER 10 minutes may have passed before being disseminated into the delivery data stream to the receiving units and the end-user/motorist on the highway.

If you purchase a new BMW with the Nav option, you're stuck with information from ClearChannels' Airwatch Traffic division.